Draw-bench speed controls



c. FRAZIER DRAW BENCH SPEED CONTROLS June 27, 1933.

Filed Feb. 25, 1952 Patented June 27, 1933 UNITED STATES PATENT OFFICECHARLES 'FRAZIEBQ OF ELLWOOD CITY, PENNSYLVANIA, ASSIGNOR TO NATIONALTUBE l COMPANY, A CORPORATION OF NEW JERSEY DRAW-BENCH SPEED CONT-BonsApplication led February 23, 1932. Serial No. 594,623.

My invention relates to tube draw-benches. These generally include adie, a chain moving away from this die and travelling pliers constructedto engage this chain while clamping the point of a tube projectingthrough the die, whereby the tube proper is drawn through the latter.This reduces the size of the tube because the frictional resistanceoffered by the metal to being pulled through the die increases the pull,exerted by the pliers on the tube, to beyond its elastic limit when itbecomes plastic, the tube then elongating and correspondingly decreasing1n cross-section. Tf this distortion is suddenly begun there is dangerof the point on the tube being pulled off, and it is common practice tobegin to draw at a slow or base speed and to afterwards increase thisspeed to the determined maximum drawing speed. Varying the speed of thechain accomplishes this, much time being lost because it is donemanually and tween the slow beginning of thedraw and this speedincrease.

' One of my objects is to provide a machine including the abovementioned elements and having an automatic control' for the chain sothat elongation of a tube may be begun at a base speed which immediatelyincreases to a predetermined maximum drawing-speed. Other objects willbe understood from the following disclosure.

Having reference drawing:

Figure 1 is a top plan of a tube drawbench incorporating one'form of myinvention.

Figure 2 is a side elevation of Figure 1.1

Figure 3 is a schematic drawing of the electrical circuit, and l Figure1 is a modification of Figure 3.

The drawing shows a draw-bench 1 having a driven chain 2 that is engagedby a set of pliers 3 which themselves engage the point to theaccompanying of the tube 4 and draw it through a die 5.

The operation of draw-benches of this general character is so well knownthat it will not he described other than this.

The pliers 3 have a depending arm 6 that is fixed to a cable 7, thelatter ring on there is a considerable lapse be-` sheaves 8 arranged `ateach end of the bench and being wrapped about a drum 9. This drum isgeared to a motor 10 through a reduction unit 11. This arrangementenables the quick return of the pliers 3 from the end of their stroke tostarting position independthe eifect'of the shunt-field 16, which willin .y

turn cause the motor speed to vary. An electromagnetic switch 18 isarranged to shunt the shunt-coil 16 by the resistance 17 and isconnected for operation by the generator 12.

Withthis control it is possible to practically immediately jump thespeed of the chain 2 from a slow or base speed to a predeterminablemaximum drawing-speed. This results from the fact that the value of theresistance 17 may be adjusted so that the maximum speed of the motor isproperly proportioned to drive the chain 2 at a maximum drawingspeed.The electromagnetic switch 18 will, however, eectively shortfcircuitthis resistance so that the shunt-field coil 16 holds the motor down todraw-starting speed.y Therefore, when the pliers 3 are placed inengagement withthe chain 2 the draw .will be started at the properspeed. This vmotion will be practically immediately communicated throughthe various connections described to rotate the generator 12 which willgenerate an operative current for the switch 18.' This places theresistance 17 in effective series with kthe shunt-field 16, cutting downits strength and allowing the motor to pick up to full tube-drawingspeed. l

A modification of this control may consist vin having the resistance 17shunted by a mechanical switch. This mechanical switch is generallyindicatedby the number 19 as operating upon the centrifugal principle.The shaft of this switch will, of course, be belted to the shaft of themotor 10 in the same manner as the generator 12.

To prevent the high speed of the motor 10 being communicated to thegenerator 12, when driving the pliers 6 back to starting position, aratchet clutch 20 of any suitable construction may be interposed -in thebelt drive. This also prevents the operation of the centrifugal switch19, if used, during this return movement. l

Although I have shown and described a specific form of my invention inaccordance with the patent statutes, I do not intend to limit myselfexactly thereto, except as described by the following claims.

I claim:

1. A machine including a die, a draw- ,.chain, tube pliers that canengage said chain,

a compound-wound electric motor arranged to drive said chain, aresistance for the shunt winding of said motor, an electromagneticswitch arranged to render said resistance operable, a cable arrangedtomove said pliers independently of said chain, a motor arranged todrive said cable, anda generator I connected to said electromagneticswitch and arzlinged for operation by movement of said ca e.

2. A machine including a die, tube pliers that can engage saidpound-wound electric motor arranged to drive said chain, a resistanceforthe shunt winding of said motor, a centrifugally operated swltcharranged to render said resistance operable, a 4cable arranged to movesaid pliers independently of said chain, a motor arranged to drive saidcable, and means operable by motion of said cable to rotate saidcentrifugally operated switch.

3. A machine including a die, a drawchain, pliers that can engage saidchain, a

a' draw-chain,

Vmotor. arranged to drive said chain, means for varying the speed ofsaid motor, a cable arranged to move said pliers independently of saidchain, a motor arranged to drive said cable and means operable by motionof said cable for controlling said iirst named means.

In testimony whereof, I have hereunto set my hand.

CHARLES FRAZIER.

chain, a com-

